Composite brake shoe



July 5, 1932. A. L. BOEGEHOLD COMPOSITE BRAKE SHOE Filed April 15, 1951 Patented July 5, 1932 UNITED STATES PATENT OFFICE ALFRED I. BOEGEHOLD, OI DETROIT, MICHIGAN, ASSIGNOR 'I'O GENERAL MOTORS RE- SEARCH CORPORATION, 01 DETROIT, MICHIGAN, A CORPORATION OF DELAWARE COMPOSITE BRAKE SHOE Application med April 18, 1931. Serial No. 529,682.

This invention relates to brakes and particularly to internal brakes such as are used in connection with the wheels of motor vehicles.

An object of the invention is to provide an improved shoe for such a brake. A more specific object is to prevent the curlin of the shoe under the influence of unequal eat conditions at the surface of the shoe and along the inner arc of its web.

A further specific object is to construct such a shoe in a way to facilitate the transfer of heat from the braking surface to the inner ed e of the web.

s a still further object the shoe is so made that the web tends to lengthen and thereby maintain conformity between the arc of the lining-carrying surface and the arcuate surface of the drum when the radius of the latter increases under the influence of heat.

Economy is a still further object and is made possible by the construction of the shoe part1 of steel and partly of aluminum or an alummum alloy, instead of wholly of aluminum, the parts being so related that the shoe shall accomplish the above stated objects.

Other objects and advanta es will be understood from the following escription.

Brake shoes designed to possess the above advantages are shown in the drawing.

Fig. 1 is a view in side elevation.

Fig. 2 is a sectional view on line 22 of Fig. 1. ig. 3 is a sectional view before the addition of the aluminum casting.

Fi 4 is a view in side elevation of a modified orm.

Fig. 5 is a perspective of a part of the shoe shown in Fig. 4:. 7

Referring first to Figs. 1 and 2, the brake shoe is made from two -shaped steel stampings 5 and 7, each including a web 9 and a flange 11. The webs 9-9 are back to back, and the flanges extend away from each other. These flanges are intended to carry suitable brake lining. Apertures in the webs are provided at 13 and 15, these apertures bein intended to provide pivotal connection or a cam follower and for a shoe anchor. Along the arc of the shoe formed by the flanges 11 11, the mid portion is depressed from pomt 17 to point 19. There are apertures as at 21 and 23 through the flanges in this depressed region. The two webs are formed with an Intermediate cut-out portion. This portion maybe said to begin at points 25 and 27. It continues with marginal lines extendmg from points 25 and 27 toward each end of the shoe. The marginal lines are then curved back toward the middle of the shoe and unite as a point 31. In this relatively deeper web adjacent the middle of the shoe are 0 enings 33. The two parts of the shoe may e secured together in any preferred manner. An aluminum or aluminum allo member 35 is cast upon the shoe so forme It fills the arcuate space from 25 to 27. It partly fills the opening made by the recess in the web portion of the steel shoe elements. It completes the arcuate lining-carrying surface by filling the region by points 17 and 19. It is locked to the steel elements by fillin the openings 33 and also the openings 21 an 23, as will be seen by reference to Fig. 2. Rivets or their equivalents 37 are used to secure the ends of the aluminum casting. to the steel shoe webs adjacent the. points 25 and 27.

With a shoe constructed as above the heat at the lining-carrying surface resulting from the application of the brake is in large measure conducted away from the surface of the shoe by the aluminum casting to the inner part of the web. When the brake is first applied the heat at the surface of the shoe exceeds that in the web and there results a well known tendency to curl, so that the shoe fails to conform to the drum as it should. By the use of the aluminum element, the heat is more readily carried to the inner edge of the web to prevent this curling. The attachment of the aluminum casting at points 37 causes the expansion thereof to tend to expand the inner portion of the shoe so that the whole shoe, instead of curling, tends to flatten. Its arcuate lining-carrying surface tends therefore to assume a longer radius as the drum flange assumes a longer radius under the influence of heat. A shoe so constructed should therefore maintain drum contact throughout the range of braking action. The construction is not only simple and easily made but as will be readily appreciated, such a shoe will be much cheaper than a shoe made wholly from the relatively more expensive aluminum.

Figs. 4 and 5 illustrate a modification. In this second form the aluminum element 35' is made by casting the same independently of the steel shoe members. Its shape is that shown in Fig. 5. It has apertures 51 at its ends and other openings 53 near the middle of the shoe. The arcuate surface is formed with a channel 55 from the sides of which are flanged portions 57. The steel portion of the shoe is quite similar to that in the form first described. The central portions of the flanges 11 are cut away in the region between numerals 17 and 19, so that the parts 57 of the aluminum element may occupy the region of the cut-away portions of the steel flanges when the web portions of the steel parts are received within the slot 55. Rivets 37 as before secure the aluminum element to the steel parts extending through the openings 51. Other fastening means 59 secure the bowed part of the aluminum element to the steel webs as clearly seen in the drawing, these fastening means extending through holes 53. The function of the aluminum element is the same as before. It carries from the heated shoe surface much of the heat to the inner portion of the web and prevents the curling of the shoe due to a hot surface and a relatively cool web. The expansion of the aluminum element between fastening means 37 also tends to expand the shoe as a whole and flatten its surface so as to permit it to conform to the arcuate surface of the drum as the latter increases its radius under the influence of heat. Again the use of steel instead of making the shoe wholly of aluminum is an element of economy.

I claim:

1. A brake shoe comprising a first portion of relatively lesser coefiicient of expansion and including an intermediately inter.- rupted lining-carrying flange and a stiffening web, said web having an intermediate recess, and a second portion of relatively greater coeflicient of expansion, said second portion being terminally attached to the web of the first portion at the ends of the recess and having an intermediate part occupying the interruption of the flange of the first part, whereby said second portion conducts heat from the surface of the shoe to the inner portion of its web, and whereby the expansion of said second portion between its point of attachment with the web flattens tge arcuate lining-carrying surface of the s 0e.

2. A brake shoe comprising a first portion of steel having an interrupted liningcarrying flange and a web, said web being intermediately recessed, and a second ortion containing aluminum as a major e ement, said second portion being of substantially segmental shape, a part of said second portion occupying the interru tion of the lining-carrying flange of the f: means to connect the ends of said segment to spaced oints of the steel web.

3. A bra e shoe comprisinga substantially segmental shaped portion, said portion having a slot in its arcuate surface and a transverse flange adjacent the mid portion of the slot, a steel portion having an interrupted lining-carrying flange and a web, ortions of said web being received within said slot, and said transverse flange occupying the interrupted part of the steel flange, and means to secure said component parts of the shoe together.

4. A brake shoe having an intermediately partially interrupted steel web and an intermediately interrupted steel lining-carrying flange, an aluminum casting having a part occupying the interruption of the steel flange and a second part at least partially occupying the interruption of the steel web, and means to secure said steel and aluminum elements together.

5. The invention defined by claim 4, said last-named means includin attaching members at the ends of the a uminum casting whereby the ex ansion of the casting may flatten the arc of the composite shoe.

6. A composite brake shoe of aluminum and steel, said shoe having a web and a flange, each of said parts having an intermediate porgion of aluminum and end portions of stee 7 A composite brake shoe, said shoe having a web and a flan e, each of said shoe parts having an interme iate portion made from a metal having a relatively greater coeflicient of expansion and end portions made from a metal having a lesser coeflicient of expansion.

8. The invention defined by claim 7, said portions of greater coefficient of e ansion being continuous whereby the excesslve heat at ]the flange of the shoe is conducted to the we 9. The invention defined by claim 7 said portions of greater coeflicient of ex ansion also having a high thermal conductivity so that the heat distribution occurs rapidly.

In testimony whereof I aflix my signature.

ALFRED L. BOEGEHOLD.

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